Recently, the line width used for manufacturing semiconductor devices has been reduced rapidly as the degree of integration of semiconductor devices has been increased. Generally, the speed of semiconductor devices is proportional to the switching speed of gates and the signal transmission speed. The latter is determined according to the RC delay indicated in terms of the multiplication of resistance of wiring materials and electrostatic capacity of interlayer insulating films. As the design rules of semiconductor devices are reduced, the speed of a high-density chip is determined according to the RC delay rather than the speed of gates. Therefore, in order to manufacture high-speed chips, conductors having a low resistance and insulating materials having a low dielectric constant should be used. For this reason, the conventional aluminum wiring is replaced with copper wiring, and the development of insulating films with a low dielectric constant is in progress. The use of the low dielectric materials increases the speed of semiconductor devices and decreases the power dissipation and crosstalk noise.
In the meantime, a general example of interlayer insulating materials of semiconductor devices is SiO2 manufactured in the gaseous vapor deposition method having a dielectric constant of 4.0, and silicate doped with fluorine (F—SiO2) is applied for some devices as a low dielectric material. However, in case of F—SiO2, it may be difficult to lower the dielectric constant to 3.5 or less since the state may thermally become unstable as the content of fluorine is increased.
Recently, many organic and inorganic polymers having a low polarity and a high thermal stability have been presented to solve this problem. Organic polymers having a low dielectric constant are known to include polyimide resins containing or not containing fluorine, polyarylene ether resins, polyaromatic hydrocarbon resins, etc. Most of these organic polymers have a dielectric constant of 3.0 or less. However, they have a very high linear expansion coefficient, and also have a low glass transition temperature and thus elasticity thereof remarkably decreases at a high temperature. The resulting low thermal stability can deteriorate the reliability of devices. Recently, in order to solve thermal stability problems of organic polymers, the development of organic silicate polymers using a sol-gel process has emerged. Organic silicate films are obtained by hydrolyzing and condensing organic silanes, and curing them. Polysilsesquioxane has a comparatively low dielectric constant of less than 3.0 and is stable at 450° C. However, the dielectric films prepared with polysilsesquioxane may crack at >1 μm due to contraction stress during a hardening process, and the dielectric constant of the films is in the range of 2.7 to 3.1. Therefore, it is not sufficient for the material having a good mechanical property and a dielectric, 2.5 or less which is necessary for the semiconductor process in the future.
In order to form insulating films having a dielectric constant of 2.5 or less, it has been proposed a method of adding an organic polymer template to polysilsesquioxane and forming low-density insulating films having nano-pores through pyrolysis after hardening. However, this method is problematic in that the strength of low-density insulating films is not sufficient; it is likely for organic materials not to be decomposed completely but to remain; the sizes of pores are increased if the compatibility between organic polymers and polysilsesquioxanes is lowered; etc. In addition, porous low dielectric films have been prepared by using an organic polysiloxane manufactured through hydrolysis and condensation of general alkoxy silanes under a basic condition. However it is difficult to obtain siloxane polymers having sufficient mechanical properties.
While studying organic polysiloxane resins and compositions in order to manufacture insulating films having a low dielectric constant and superior mechanical properties, the inventors of the present invention have found that organic polysiloxane resins manufactured through hydrolysis and condensation of a specific silane compound under a basic condition have more superior mechanical properties compared to porous low dielectric films manufactured by using organic polysiloxane resins manufactured through hydrolysis and condensation of only a general silane compound under a basic condition or organic polysiloxane resins and organic polymers manufactured through hydrolysis and condensation under an acidic condition, and completed the present invention based on the above.